Fix createTicket duplicate-key retry handler for PHP 8.2

PHP 8.2 strict mysqli mode throws mysqli_sql_exception on duplicate key
rather than returning false from execute(). Replace the old if/else errno
check with try/catch on mysqli_sql_exception, re-throw non-1062 errors,
and use random_int range 100000000-999999999 (no leading zeros) for the
retry ID.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

models/TicketModel.php

@@ -440,20 +440,25 @@ class TicketModel {
             $visibilityGroups
         );
 
+        try {
             if ($stmt->execute()) {
                 return [
                     'success' => true,
                     'ticket_id' => $ticket_id
                 ];
-        } else {
+            }
+            return ['success' => false, 'error' => $this->conn->error];
+        } catch (mysqli_sql_exception $e) {
             // Handle duplicate key (errno 1062) caused by race condition between
             // the uniqueness SELECT above and this INSERT — regenerate and retry once
-            if ($this->conn->errno === 1062) {
+            if ($e->getCode() !== 1062) {
+                throw $e;
+            }
             $stmt->close();
             try {
-                    $ticket_id = sprintf('%09d', random_int(100000000, 999999999));
-                } catch (Exception $e) {
-                    $ticket_id = sprintf('%09d', mt_rand(100000000, 999999999));
+                $ticket_id = (string)random_int(100000000, 999999999);
+            } catch (Exception $ex) {
+                $ticket_id = (string)mt_rand(100000000, 999999999);
             }
             $stmt = $this->conn->prepare($sql);
             $stmt->bind_param(
@@ -470,14 +475,14 @@ class TicketModel {
                 $visibility,
                 $visibilityGroups
             );
+            try {
                 if ($stmt->execute()) {
                     return ['success' => true, 'ticket_id' => $ticket_id];
                 }
+            } catch (mysqli_sql_exception $e2) {
+                // Second attempt also hit duplicate — extremely rare
             }
-            return [
-                'success' => false,
-                'error' => $this->conn->error
-            ];
+            return ['success' => false, 'error' => 'Failed to create ticket due to ID collision'];
         }
     }